Cristiano Ronaldo turns 35 in February and is now in the autumn of his career.

But because he keeps himself in such incredible condition, there’s no reason why the Portuguese legend can’t play on into his early-40s.

That said, his body will inevitably begin to let him down at times. That’s just part and parcel of getting old.

Ronaldo was subbed off before full-time in Juve’s 2-1 win over Lokomotiv Moscow in the Champions League last week, when the score was still level at 1-1.

And during Sunday night’s Serie A clash against AC Milan, Maurizio Sarri withdrew his star man after just 55 minutes, replacing the five-time Ballon d’Or winner for Paulo Dybala.

Dybala went on to score the only goal of the game in the 77th minute, keeping Juve top of the Serie A table in the process.

Ronaldo’s reaction to being substituted, however, was the biggest talking point from the game.

The veteran forward appeared to be angry with the decision to bring him off and went straight off down the tunnel.

The Guardian’s report states: “Despite producing a lacklustre display, Ronaldo gave coach Maurizio Sarri a dirty look, muttered something under his breath and walked straight down the tunnel.”

Indeed, Italian journalist Tancredi Palmeri tweeted a video showing Ronaldo saying something to Sarri as he walked towards the tunnel.

“Everyone seems to agree that in the midst of the words there is at least one ‘vai pra o caralho’, or ‘go away’,” Palmeri added in a separate tweet.

Meanwhile, another tweet was posted by a Juve fan claiming Ronaldo had intimated that he was, in fact, injured and requested to be subbed out.

How true this actually is, however, is unclear.

Sky Sport Italia - per Football Italia - then confirmed that Ronaldo had left the Allianz Stadium before the match had even finished, which seemed particularly curious and merely added fuel to the fire.

The former Real Madrid star left the stadium three minutes before the end, although it’s unclear why.

Was he injured? Was he just angry? Nobody seems to know for sure at the moment.

Sarri told Sky Sports Italia, per Football Italia, after the match: “We must thank Ronaldo, because he made a sacrifice to be there at all tonight in a difficult situation. He did everything possible to play, but I saw he was not well and thought it best to take him off.

“It’s only natural a player is going to be irritated to leave the pitch, especially when he worked so hard to be there.

Over the last month, he has had this little knee problem, he had a knock in training and it hurt the collateral ligament. When he trains at high intensity or plays, it unbalances him, so he ends up overcompensating and it damages the calf and thigh muscles.

“It is affecting his performances and he is not at his best at the moment. All players who are trying to give their best will have at least five minutes of being annoyed when they are substituted, but a coach would in general be much more worried if he didn’t seem upset.”